Energy efficient and cost effective power, fuels and chemicals production process schemes for efficient and environmentally friendly utilization of hydrocarbon fuel resources such as coal, biomass, solid waste, and natural gas require advanced gas separation techniques. Many of these production processes involve the production and subsequent separation/purification of synthesis gas (syngas), where the syngas is generated via various means, largely depending on the target application and feedstocks utilized (e.g., steam methane reforming, partial oxidation, solid fuels gasification). After syngas cleanup, more hydrogen is produced by converting carbon monoxide in the syngas to carbon dioxide using steam via water gas shift (WGS) reaction. At this stage, syngas is predominantly composed of H2, CO2 and H2O (steam) with trace impurities such as CO, H2S, NH3, N2, particulate matter, and metals. H2 can then be separated from the syngas for use as fuel while the CO2 rich retentate stream is compressed and subsequently sequestered or re-used. Techno-economic studies indicate that hydrogen separation and carbon dioxide capture at the syngas operating conditions (high temperature and high pressure) in the vicinity of WGS reactor results in higher efficiency and substantial cost savings. However, application of commercially available sorption- and membrane-based H2/CO2 separation techniques is limited to low temperatures (<100° C.) far below the syngas operating temperatures (>250° C.) process efficient integration.
A selected class of H2 selective polymeric benzimidazole-based materials, known as polybenzimidazoles (PBI) has exceptional thermal and chemical stabilities for operation at realistic syngas operating conditions and chemical environments. To realize complete advantage of the PBI membranes comprised of these PBI materials at industrial scale, their translation into high surface area membrane (small footprint) deployment platforms such as hollow fiber with thin selective layers is required. Besides gas separation, porous PBI hollow fibers are also attractive for solute removal from liquids and organic solvents due to high chemical stability of PBI. PBI hollow fibers are hydrophilic due to the presence of amine group and expected to reduce fouling propensity especially in water purification application. However, the complex chemical and solution properties of PBI present a significant challenge to prepare mechanically robust high performance PBI hollow fiber using an environmentally benign fabrication process.